Card-to-Computer Transfer Speed: CompactFlash Readers
This page was last updated on April 13, 2011

If you're faced with copying pictures from a stack of CompactFlash cards to a Mac or PC, and time is of the essence, this section of the CF/SD Performance Database is for you. SD/SDHC/SDXC card readers are covered on a separate page.

The Readers

Almost all of the readers below support the UDMA protocol found in the fastest CompactFlash cards to emerge since mid-2006. For the quickest-possible transfer of photos from speedier memory cards to your computer, a well-engineered UDMA-capable reader is a must.

This reader was the first USB 2.0 model to emerge with support for the UDMA protocol for faster transfers with newer high-speed CompactFlash cards and can still hold its own against UDMA USB 2.0 readers that have emerged since then.

The USB connector on this small CompactFlash-only USB 2.0 reader can be plugged directly into a computer's USB port, or it can be connected via the included extension cable.

This CompactFlash-only ExpressCard adapter is compatible with computers equipped with ExpressCard 54 slots and has been available to date in two versions, both of which look the same and ship in similar or identical packaging, but offer different performance. ExpressCards can be designed to communicate internally with the host via USB 2.0 or PCIe. The first version of this adapter appears to use USB 2.0, and delivers read speeds commensurate with a modern USB 2.0 card reader. The second version is PCIe and is noticeably faster, but suffers from some compatibility problems. Both have been tested and the results are below.

As Apple's ExpressCard-capable MacBook Pro laptops have a narrower ExpressCard 34 slot, this adapter from Delkin is effectively for PCs only (and then, only ones with an ExpressCard 54 slot). Unlike CompactFlash card adapters fitted for 34mm-wide ExpressCard 34 slots, which require the adapter portion that holds the CompactFlash card to sit entirely outside the slot, a 54mm-wide ExpressCard 54 slot allows for a design that takes the CompactFlash card inside the slot along with the adapter.

More importantly, this type of adapter can - and both versions of the Delkin ExpressCard 54 CompactFlash model do - use a traditional recessed pin-style channel for the CompactFlash card, which we've found to be more durable and less prone to pin breakage than the current crop of ExpressCard 34 CompactFlash adapters, including ones from Delkin and Synchrotech.

For road warriors, there's one more benefit: the Delkin ExpressCard 54 CompactFlash adapter, when empty, doesn't stick out of the card slot by more than one or two millimetres, at least with our IBM/Lenovo T60 laptop. This means the adapter can ride in there all the time, so that when you have your laptop with you, you have your reader with you too. Additionally, it's possible to insert and remove just the CompactFlash card from this adapter without first removing the adapter from the computer, further extending its convenience.

Generally speaking, we've found CardBus and ExpressCard adapters to be a pain: between card incompatibilities, driver problems and broken connector pins, they are a good advertisement for sticking with external USB and FireWire readers. The first version of the Delkin ExpressCard 54 CompactFlash adapter has so far hummed along with none of the drama of certain other adapters, and that has been a pleasant change.

The second version, which is generally quicker than the first version, isn't quite as trouble free. More than a few CompactFlash cards, even fast ones, slow to a turtle's pace of less than 1MB/second in the PCIe variant of the Delkin ExpressCard 54 CompactFlash adapter. Plus, our normally rock-solid T60 test machine crashed twice during benchmarking. In short, the second version may be speedier, but the first version (which is probably no longer shipping) is more compatible and seemingly more reliable too.

The slowdowns and crashes we experienced with the second version of the Delkin ExpressCard 54 CompactFlash adapter mirror almost exactly the problems we saw when testing the Synchrotech CFExpressPro+, an ExpressCard 34 adapter. This likely means that both share the same controller.

This four-slot, CompactFlash-only USB 2.0 reader is intended for high volume workflows. It incorporates inside its hard-plastic shell a powered USB hub which, in addition to serving its own four reader slots, enables additional ImageRouter or other USB readers to be linked to it courtesy of a single USB port, for additional simultaneous card download capacity. The ImageRouter connects to the computer via a detachable cable and comes with a 100-240VAC adapter (which is required for the reader to work).

The Delkin ImageRouter is available on its own or in a kit with the company's BackupandBurn transfer and disc burning application.

This USB 2.0 reader, which accepts CompactFlash, SD/SDHC and various other memory card formats, connects to the computer via a short, non-detachable cable that's an ideal length for use next to a laptop. An extension cable is included for when the reader needs to sit further from the computer. The card slots can be slid flush with the reader's front when in use (as shown in the picture), then slid back inside the reader's shell for storage and travel.

This CompactFlash and SD/SDHC USB 2.0 reader features a pop-up design that, when popped down, keeps its twin card slots protected. It connects to the computer via a detachable cable.

Though the Lexar's black popup section - which is the actual reader portion - and its semi-translucent frame aren't intended to be separated, it's possible to do so to save space in an overstuffed laptop bag. The hinge mechanism that holds the two together can be separated without much effort and without damaging the unit. We did this, then completed the transformation by first putting some gaffer tape to cover openings on the black section's base, followed by small grippy feet (left over from a portable hard drive kit) onto the base's four corners.

The read speeds for the Delkin Reader-39, Hoodman RAW UDMA FireWire 800, Lexar Professional UDMA FireWire 800 and Synchrotech CFFire800 Pro are effectively identical to this SanDisk reader, because all four utilize the same controller from Oxford. That said, the SanDisk Extreme FireWire reader has the nicest industrial design of the bunch. The Delkin, Hoodman and Synchrotech feature a non-removable cable, which reduces their travel ruggedness, while the Lexar's insert/eject mechanism is poor (though it's the only one to provide twin FireWire ports for daisy-chaining).

SanDisk Extreme III USB (original version)

This CompactFlash and SD/SDHC USB 2.0 reader is one of the most dependable and goof-proof readers we've ever used. Its lack of support for the UDMA protocol, however, means the quickest CompactFlash cards revert to operating in the slower PIO transfer mode which, as the results show, puts the brakes on throughput for this memory card type. This now-discontinued reader may not be a CompactFlash speed demon, but it remains a favourite here because it just works.

Starting in July 2008, SanDisk began shipping a new version of this reader that supports the UDMA protocol for quicker transfers from newer CompactFlash cards that also support UDMA. At the same time, it became a CompactFlash-only reader; SanDisk removed the SD/SDHC slot in the redesign.

Slated to ship in November 2008, this four-slot reader accepts CompactFlash (CF I only, which means thicker CF II cards such as the Hitachi Microdrive won't fit), SD/SDHC and numerous other memory card formats.

The ImageMate All-in-One USB 2.0 includes a removable, magnetically attached three-legged stand. It connects to the computer via a detachable cable. The unit we've tested is not final production, but is expected to be representative of the performance and compatibility of the reader that will ship to stores.

ExpressCards can communicate with the host computer via slower USB 2.0 or faster PCIe; this CompactFlash-only ExpressCard 34 adapter uses the latter method, and it makes for throughput that rivals the fastest external readers with some cards. As the results show, certain card brands and models perform well in the CFExpressPro+ - a number deliver read speeds of over 40MB/second - but a sizeable minority work at less than 1MB/second, which is really the same as saying that these cards are incompatible with this adapter.

The shallow card slot of the CFExpressPro+ makes it possible to slide a card in slightly off angle, just off angle enough for the card to bend several of the adapter slot's pins. By comparison, the deeper slot of a typical external card reader means the card has straightened out by the time it reaches the pins at the rear of the slot.

We bent several of the CFExpressPro+'s pins during testing, despite taking care to insert each card straight on, which meant the adapter had to be replaced before we could complete the testing. The same thing occurred in day-to-day use of a Delkin ExpressCard 34 several months ago, and it features the same shallow slot design, so be aware of this apparent limitation in this type of CompactFlash adapter. And finally, we have also encountered the occasional OS X kernel panic when using the CFExpressPro+, with a Mac that is otherwise stable and contains a fresh operating system install.

The CompactFlash read speed results below were generated with QuickBench 4, a cross-platform benchmarking utility we like because it produces numbers that equate closely to real world performance when using the operating system to copy digital SLR JPEG and RAW files from a memory card to the computer. QuickBench was set to
Large Test (2-10MB),
Allow Cache Effects was turned off and 3 test cycles were run. All cards were secure erased and then formatted in a Canon EOS-1D Mark IV or Canon EOS 5D Mark II before testing.

Use the NEXT FOUR READERS and PREVIOUS FOUR READERS links to navigate through all the reader data. The fields marked in
blue represent the fastest read speed for that card. In the case of an incompatibility between card and reader, the field is marked
--Error--.

To view all the results for this card type in a single table, click here. (Note that it may take several seconds for the large table to load.)